This invention relates to a process for the production of poly(arylene sulfide). In one aspect, this invention relates to a process of producing high molecular weight linear poly(arylene sulfide). In another aspect, this invention relates to the recovery of useable poly(arylene sulfide) from low molecular weight slime. In still another aspect, this invention relates to the recovery of particulate poly(arylene sulfide) of higher molecular weight from a low molecular weight poly(arylene sulfide) waste.
In applications such as in the production of fibers and films from arylene sulfide polymers, linear poly(arylene sulfide) is preferred to branched types. It is desirable that the linear poly(arylene sulfide) have as high a molecular weight as possible in order to meet specialized product specifications. While high molecular weight non-linear poly(arylene sulfide) can readily be made by the addition of branching agents, such as trichlorobenzene, to the polymerization process, high molecular weight linear poly(arylene sulfide) cannot be made by this method. Previous methods to produce high molecular weight poly(arylene sulfide) without the use of branching agents include crosslinking the polymer, extracting impurities from the polymer, and the use of modifying materials such as sodium carboxylate in the polymerization process.
It would be beneficial if an improved method could be devised to produce high molecular weight linear poly(arylene sulfide).
Linear and non-linear poly(arylene sulfide)s can be produced by various processes using polyhalo-substituted aromatic compounds such as dihalobenzenes and trihalobenzenes. After the poly(arylene sulfide) is polymerized, the poly(arylene sulfide) must be recovered from the polymerization mixture. There are several processes for recovering linear and non-linear poly(arylene sulfide)s from the polymerization mixture. Two such processes are the solvent flashing process and the water quench process. In the water quench process of recovering these poly(arylene sulfide)s, a waste product called poly(arylene sulfide) "slime" is separated from the useful product. The slime separated in this process contains low molecular weight poly(arylene sulfide) fines and heretofore has been generally discarded.
It would be beneficial if a method could be devised to recover some useful product out of this discarded low molecular weight poly(arylene sulfide) material in the slime.